Biology test 3 (notes)

MPF

(mitosis promoting factor) -has to be present for mitosis to occur -regulates cell cycle, related to cancer

the rule of addition

- For events occurring more than one way (ex: the probability of rolling som of 5 with dice= - 1:1/6 X 4:1/6= 1/36 -2:1/6 X 3:1/6= 1/36 -3:1/6 X 2:1/6= 1/36 -4:1/6 X 1:1/6= 1/36 1+1+1+1/36= 4/36 or 1/9)

the rule of multiplication

- for simultaneous, independent events (example the probability of rolling two 4's on a dice= 1/6 X 1/6=1/36

Meiosis

- usually reproductive -with a diploid cell (2n) and produces 4 new cells with half as much DNA as the original cell (haploid). -start w/ diploid --- end with 4 haploid

Telomerase

-An enzyme that catalyzes the lengthening of telomeres. -"immortal" -reverse transcriptase -fills the gap at 5' ends of chromosomes -involved in stem cells, aging, and cancer

Cell Cycle: Interphase stages

-G1: life as usual -S: copy DNA -G2: prep for division

semiconservative replication

-Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand -something old & something new

Mitosis

-Mitosis copies cells and makes 2 identical duplicates -start with one diploid cell---end with 2 diploid cells -start with one haploid cell---end with 2 haploid cells

Cell Cycle: Cytokinesis stage

-division of cytoplasm/cell splits in 2

endosymbiont theory

-explains that eukaryotic cells may have evolved from prokaryotic cells

Cell Cycle: Mitosis stages

-prophase: chromatin condenses making the chromosomes visible - pro-metaphase: nuclear envelope breaks down -metaphase: the chromosomes become aligned at the equatorial plane -anaphase: sister chromatids separate and the resultant daughter chromosomes move toward the poles -telophase: daughter chromosomes reach the poles and form 2 new nuclei

Mitochondiral DNA (mtDNA)

-the small circular chromosome found inside mitochondria

binary fission (prokaryotes)

-the splitting of a cell in two after duplicating/copying the DNA--creates identical copies (clones) -A form of asexual reproduction

what does the probability of all possible outcomes add up to?

1

Which is true of RNA? 1. A purine always forms a complementary base pair with a pyrimidine. 2. A phosphate group is a nucleotide attached to the 3' carbon in ribose 3. It is always single strand and the nucleotides do not participate in base pairing 4. Successive nucleotides in a strand are connected by hydrogen bonds 5. The percentage of the purine A always equals the percentage of the purine U

1. A purine always forms a complementary base pair with a pyrimidine.

If one strand of DNA reads TACG from 5' to 3' then the other complimentary strand will read ______ 3' to 5'. 1. ATGC 2. CGUA 3. AUGC 4. CGTA

1. ATGC

steps of binary fission (prokaryotes)

1. Cell elongates and DNA is replicated 2. Cell expands and cell wall and plasma membrane begin to constrict 3. Cross-wall forms, completely separating the two DNA copies 4. Cells separate

Which of the following statements about RNA primase is false? 1. No RNA primase is required for the leading strand 2. RNA primase builds complimentary RNA primers using the template DNA strands in order to initiate DNA synthesis 3. If the DNA template strand reads AATT then the RNA primase will build a primer reading UUAA. 4.More RNA primase is required for the lagging strand than the leading strand.

1. No RNA primase is required for the leading strand

What is the difference between the leading strand and the lagging strand in DNA replication? 1. The leading strand is synthesized continuously in the 5'→3' direction, while the lagging strand is synthesized discontinuously in the 5'→3' direction. 2. There are different DNA polymerases involved in elongation of the leading strand and the lagging strand. 3. The leading strand requires an RNA primer, whereas the lagging strand does not. 4. The leading strand is synthesized in the 3'→5' direction in a discontinuous fashion, while the lagging strand is synthesized in the 5'→3' direction in a continuous fashion.

1. The leading strand is synthesized continuously in the 5'→3' direction, while the lagging strand is synthesized discontinuously in the 5'→3' direction.

mendelian genetics rules (3)

1. Two trait alleles per character 2. One trait dominant, one recessive 3. If >1 character considered then each character is on a separate chromosome (unlinked).

Metaphase checkpoint

1. all chromosomes must be attached to spindle apparatus

G1 checkpoint

1. cell size must be adequate 2. nutrients must be sufficient 3. cell must be undamaged 4. social signals must be present

G2 checkpoint

1. chromosomes must be replicated successfully 2. DNA must be undamaged 3. activated MPF must be present

5 Key enzymes for copying DNA

1. helicase 2. RNA primase 3. DNA polymerase III 4. DNA polymerase I 5. DNA ligase

Which of the following is true about the end replication problem? 1.prokaryotic cells do not suffer from the end replication problem 2.eukaryotic chromosomes grow in length after every cell division 3.telomeres are present in prokaryotic DNA 4.eukaryotic stem cells have deactivated telomerase enzymes

1.prokaryotic cells do not suffer from the end replication problem

If you cross a homozygous dominant plant with a heterozygous plant what are the odds of getting homozygous dominant offspring?

1/2 or 50% (the other 50% is heterozygous)

A growing strand of DNA only elongates in which direction? 1. direction toward the Okazaki fragments 2. 5' to 3' direction 3. 5' to 3' direction on one strand and the 3' to 5' direction on the other 4. 3' to 5' direction

2. 5' to 3' direction

In a typical eukaryotic animal lifecycle, which of the following functions is not done through mitosis? 1. repair and replacement of components within multicellular organism over its lifespan 2. making reproductive gametes such as eggs or sperm 3. growth and development of a multicellular organism from a unicellular zygote 4.growth of a non-malignant tumor in a eukaryotic organism

2. making reproductive gametes such as eggs or sperm

Which of the following replicate themselves in the same way? 1. eukaryotic cells, prokaryotic cells, and mitochondria 2. prokaryotic cells, mitochondria, and chloroplasts 3. eukaryotic cells and chloroplasts 4. eukaryotic cells and prokaryotic cells 5.eukaryotic cells and mitochondria

2. prokaryotic cells, mitochondria, and chloroplasts

Sometimes, cytokinesis does not follow mitosis. The cell that results would have 1. two nuclei but with half the amount of DNA. 2. two nuclei. 3. high concentrations of actin and myosin. 4.two abnormally small nuclei. a single large nucleus.

2. two nuclei.

A group of scientists used telomerase to extend the life span of normal human cells. How might adding telomerase affect cellular aging? 1. Telomerase shortens telomeres and thus delays cellular aging. 2. Telomerase would have no effect on cellular aging. 3. Telomerase ensures that the ends of the chromosomes are accurately replicated and eliminates telomere shortening. 4. Telomerase will speed up the rate of cell proliferation.

3. Telomerase ensures that the ends of the chromosomes are accurately replicated and eliminates telomere shortening.

Some cells have several nuclei per cell. How could such multinucleated cells be explained? 1. The cell underwent repeated cytokinesis but no mitosis. 2. The cell had multiple S phases before it entered mitosis. 3. The cell underwent repeated mitosis, but cytokinesis did not occur. 4. The cell underwent repeated mitosis with simultaneous cytokinesis.

3. The cell underwent repeated mitosis, but cytokinesis did not occur.

In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and _____ of the last nucleotide in the polymer. 1. C6 2. the 5' phosphate 3. the 3' OH 4. a nitrogen from the nitrogen-containing base

3. the 3' OH

Cell division in bacterial cells is 1.the same as in eukaryotic cells, but does not have metaphase 2.the same as in eukaryotic cells 3.called binary fission

3.called binary fission

A bacterial cell splits into two new cells by a process called: 1. mitosis. 2. forming a cell plate. 3. forming a cell furrow. 4. binary fission. 5. duplication.

4. binary fission (bc its prokaryotic)

In the double helix structure of nucleic acids, cytosine hydrogen bonds to 1. ribose. 2. deoxyribose. 3. adenine. 4. guanine. 5. thymine.

4. guanine

Which of the following might lead to uncontrolled, over active cell division (cancer)? 1. mutations of the telomerase enzyme genes that deactivate telomerase in cells in which it should be activated 2. a mutation that causes telomeres to be unusually short 3. a mutation that results in cells that are unable to produce DNA polymerase III 4. mutations of the telomerase enzyme genes that activate telomerase in cells in which it should be deactivated

4. mutations of the telomerase enzyme genes that activate telomerase in cells in which it should be deactivated

It was primarily the X-ray diffraction work on DNA done by ________ that allowed Watson and Crick to deduce the structure of DNA. 1.Gregor Mendel 2.Louis Pasteur 3.T.H. Morgan 4.Rosalind Franklin

4.Rosalind Franklin

growth of DNA adding nucleotides only happens____to______

5' to 3'

Which of these enzymes is responsible for removing RNA nucleotides from the primer replacing them with DNA nucleotides on the 3' end of Okazaki fragments? 1. DNA polymerase III 2. ligase 3. primase 4. helicase 5. DNA polymerase I

5. DNA polymerase I

What is the fate of the two original strands of a DNA molecule after the DNA has replicated? 1. After serving as replication templates, the two original strands are rejoined. 2. Incomplete segments of the original strands end up in each newly synthesized strand. 3. After serving as replication templates, the two original strands are destroyed. 4. Nucleotides from the original strands are randomly incorporated into the new strands. 5. Each original strand ends up paired with a newly synthesized strand.

5. Each original strand ends up paired with a newly synthesized strand.

Chromatin is made up of ____. 1. DNA 2. carbohydrates 3. protein 4. both DNA and carbohydrates 5. both DNA and protein

5. both DNA and protein

haploid cell

A cell containing only one set of chromosomes (n).

diploid cell

A cell containing two sets of chromosomes (2n), one set inherited from each parent.

polynucleotide

A polymer consisting of many nucleotide monomers in a chain; nucleotides can be those of DNA or RNA.

Which of the following will undergo binary fission? (Archaea, Bacteria, Chloroplasts, Mitochondria, All of the above)

All of the above

sister chromatids

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.

leading strand

New DNA build by DNA polymerase III 5' to 3' towards the replication fork where helicase is unwinding the DNA

lagging strand

New DNA built by polymerase III 5' to 3' away from the replication fork in smaller discontinuous chunks called okazaki fragments. multiple primers are needed. one for each of the okazaki fragments

new nucleotides must join a open________ group

OH

5' & 3' (which is OH and which is Phosphate)

OH=3' P=5'

homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

antiparallel strands

Strands parallel to each other going in opposite directions (3'-5' and 5'-3')

endosymbiont

a cell living within another cell

FtsZ fibers

a type of cytoskeletal component involved in prokaryotic cytokinesis. Question 1 options:

Prokaryotic cells divide by__________________

binary fission

mitochondria and chloroplasts divide by __________ due to their evolutionary origins as prokaryotic __________

binary fission, endosymbionts

most prokaryotes have a __________ chromosome

circular

when is a test cross used?

determining an unknown genotype

origins of replication speed up ________

dna synthesis

recessive trait is masked by ____________

dominant trait

characters are coded for by ________

genes (ex- flower color__

alleles create the ___________

genotype (ex: PP, Pp, pp)

each gene (character) has its own __________________________________

genotype(2 alleles, on a homologous pair of chromosomes)

Why do cells divide?

growth/development, repair, reproduction

hybrid

heterozygous

true breeding

homozygous (eiher dom or recessive)

What bond holds the two DNA strands together?

hydrogen bonds

Binary fission image

image

Cell Cycle image

image

leading and lagging strand image

image

mitosis & meiosis image

image

semiconservative replication image

image

how are Mitochondiral DNA (mtDNA) inherited?

inherited in a direct maternal line

cell cycle stages

interphase, mitosis, cytokinesis

Chromosomes

lengthy segments of DNA

cancer develops because density inhibitions _____,_____ ____

lost, keeps dividing

How do eukaryotic cells divide?

mitosis and meiosis

Are dominant traits always more common?

no

are dominant alleles always favorable?

no (example: Achondroplasia Huntington's disease)

observable traits are the same thing as ________

phenotypes (ex- purple or white)

new nucleotides can NOT join onto a________ group

phosphate (P)

What is the backbone of DNA made out of?

phosphate and sugar

end replication problem

polymerase cannot replicate the 5' (beginning) end of the new strand because that's where the primer was. DNA strands lose 50-200 bases per replication; every time cell copies for division, a little bit of the telomere is eroded (s phase)

what do punnet squares show?

probability, meiosis and fertilization

Histones

protein molecules around which DNA is tightly coiled in chromatin

dominant allele masks _____________

recessive trait

RNA Primase enzyme (role/leading or lagging)

role: builds RNA primers so DNA polymerase III can access an open 3' OH leading/lagging: both

DNA polymerase I enzyme (role/leading or lagging)

role: removes RNA primers and simultaneously replaces them with DNA leading/lagging: both

DNA ligase enzyme (role/leading or lagging)

role: seals up gaps with Okazaki fragments leading/lagging: mostly lagging because the lagging strand has more primers, so more spots to seal

DNA polymerase III enzyme (role/leading or lagging)

role: synthesizes complementary DNA strands 5'-3' leading/lagging: both can only build new DNA 5' to 3'--> only adds onto a 3' OH that is open

Helicase enzyme (role/leading or lagging)

role: unwinds DNA double strand leading/lagging: N/A

DNA replication is _________

semiconservative

When does the cell cycle end? (hint: t)

the cell cycle ends when telomeres get too short. cells age out/retire/stope dividing

DNA replication is considered semi-conservative because ______________________

the daughter DNA molecules created each contain one template strand and one newly generated strand

Telomere

the ends of linear chromosomes